1. Field of the Disclosure
This disclosure generally relates to a pointing system and, more particularly, to an image positioning method and an interactive imaging system using the same.
2. Description of the Related Art
An interactive imaging system generally utilizes an image sensor to capture a plurality of image frames containing at least one reference point image and correspondingly controls an electronic device according to a position variation of the reference point image between image frames, such as controlling the motion of a cursor shown on a display screen. To correctly control the cursor, first it is necessary to correctly position the reference point image in the image frames.
For example U.S. Pat. No. 7,796,116, entitled “electronic equipment for handheld vision based absolute pointing system”, discloses an image positioning method. Referring to FIG. 1A, the image positioning method includes the steps of: determining an intensity value of every pixel in an image frame 9; determining a rectangular range 92 containing a reference point image 91; identifying a plurality of valid pixels within the rectangular range 92 having the intensity value higher than a predetermined threshold; and determining a coordinate of the reference point image 91 according to the intensity value and a pixel position of each of the valid pixels.
In said conventional image positioning method, it is assumed that the intensity value of noise in the image frame 9 does not exceed the predetermined threshold and the positioning of the reference point image 91 is performed based on this assumption. However, actually when there is noise existing within the rectangular range 92, the noise may cause the intensity value of a part of pixels to be higher than the predetermined threshold, such as the pixel 921 shown in FIG. 1B. In this case, if the coordinate of the reference point image 91 is calculated according to the above conventional image positioning method, the calculated coordinate may have a shift from the actual coordinate.
In addition, within the range of the reference point image 91, noise may cause a part of pixels to have the intensity value lower than the predetermined threshold, such as the pixel 911 shown in FIG. 1B. In this case, if the coordinate of the reference point image 91 is calculated according to the above conventional image positioning method, the calculated coordinate may also have a shift from the actual coordinate. If the calculated coordinate of the reference point image 91 is incorrect, it may not be able to correctly perform the desired control.
Accordingly, the present disclosure further provides an image positioning method and an interactive imaging system using the same that can eliminate the interference from noise and improve the accuracy and stability of the positioning.